SCALPELLUM 



24S 



neri and S. boiivieri are externally rather similar, but differences are to be found in the 

 carino-laterals and the inframedian laterals. The finer structure of the plates which I 



Fig. 9. Scalpelhitn convexum. a. Pupa with primordial valves and upper latus (total length 0-94 mm.). 

 b,c, d. Young specimens (total lengths 1-50, 1-91, and 4-35 mm. respectively), e. Carina, inframedian 

 latus and rostral latus of a young specimen (total length 5-62 mm.). /. Full-grown specimen, lateral view 

 (total length 15 mm.), g. Carina and carinal latera. li. The same specimen, rostral view. 



have determined by studying the types makes the differences greater than it is possible 

 to see from figures only. S. weltneri has a very hairy cuticle and S. bouvieri a cuticle 

 without hairs. They are thus all found to be good species. 



